Method of treating mineral oils



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Patented Mar. 30, 1943 METHOD OF TREATING MINERAL OILS Stanislaw Pilatand Marian Godlewicz, Lemberg,

Poland, assignors to Shell Development Company, San Francisco, Calif., acorporation of Delaware Application January 30, 1934, Serial No. 708,988

` In Poland February 6, 1933 (Cl. 19E- 13) 16 Claims.

This invention pertains to a method of separating mineral oils intofractions of different physical and/or chemical properties, and isparticularly concerned with the vtreatment of relatively viscous mineraloils, petroleum residues, lubricating oil distillates, coal tar and coaltar oils, and other hydrocarbon mixtures, with gases under pressure,said pressure being insufcient for liquefaction of the gases inquestion.

While a number of extraction methods employing various liquids asselective solvents for extracting mineral oils are well known, we havediscovered that the separation of oils into fractions may beaccomplished Without making use of liquid solvents, but by regulatingthe degree of saturation of the oil with a gaseous substance.Considerable advantages are inherent in our method of treatment, one ofwhich is that relatively loW pressures (far below liquefaction pressuresof said gaseous substances) and ordinary or elevated temperatures (notexceeding 200 C.) may be employed in carrying out the process of ourinvention. No chemical changes are involved in separating mineral oilsby the method of our invention, the treatment being of a physical andnot chemical type.

Briefly, the invention consists of introducing into a mineral oil a gasunder a superatmospheric pressure until a concentration is reached atwhich the oil separates into two phases of different specic gravities.Relative quantities and compositions of the oil portions in the phasesare regulated by maintaining suitable treating temperatures andpressures, as well as by selecting or regulating the composition of thegaseous -treating agent; as gaseous treating agents may be used:methane, ethane, carbon dioxide, hydrogen, water-gas, dry natural gas,or any other substance or a mixture of substances, which is gaseous atthe temperature and pressure employed and which is capable, on beingintroduced in the gaseous state under a superatmospheric pressure intoAthe oil being treated, to cause the separation of the same into twophases of different properties.

The process can be modified by dissolving the oil to be treated in asuitable solvent which may be of the typel of known deasphaltizingagents, such as normally liquid or liquefied hydrocarbons, as propane,propylene, normal or isobutanes, butylenes, normal or iso-pentanes,hexanes, o1' their mixtures, light straight run naphthas, or other lightaromatic-free fractions of a mineral oil; or said solvent may be chosenfrom a group of what are known as selective or naphthenic solvents, suchas liquid SO2, furfural, nitrobenzene, Chlorex dichloroethyl ether),cresylic acid, phenol, aniline, and a large number of others, theirmixtures, or solutions with diluents; We also found, that in practicingour invention auxiliary treating agents of the type of oil decolorizingagents, such as fullers earth, naphthalene, phenanthrene,dinitrobenzene, and the like, may be advantageously used either insteadof or in conjunction with deasphaltizing agents and/or selectivesolvents described hereinbefore.

In carrying out our invention in practice we prefer to dissolve themineral oil distillate or residue to be treated in a deasphaltizingagent or in a naphthenic solvent or in a mixture of both, although ourprocess is applicable in treating undissolved mineral oils. The purposeof dissolving the oil in a solvent is to modify the fractionating eiectof the gaseous treating agent, because we found -that compositions ofthe fractions obtained by our method of treating an oil, after rstdissolving the oil in a solvent, are somewhat different from thoseobtained from undissolved oils; operating conditions, such astemperatures and pressures, under which a gaseous treating agent isintroduced into the oils being separated into fractions, are also aectedby the use of either deasphaltizing or other selective solvents inconjunction with our treatment.

In the preferred form of our invention a solvent is usually added to theoil in such quantity as substantially to saturate the oil withoutcausing it to separate into two phases at the temperature used in ourtreatment. The dissolved oil is then contacted with a gaseous treatingagent under pressure, which is lower than the lliquefaction pressure ofthe 'agent at the corresponding temperature, to cause this agent todissolve in the oil solution and saturate this solution withaccompanying separation of a second heavier phase. The' light and heavyphases produced in this manner may be separated by settling or in someother manner, without changing or the two methods may alternate in aseries of consecutive treatments.

It may be desirable in a series of consecutive treatments not only tovary the treating conditions, like pressures and temperatures, -or thegaseous treating agent, but also to modify the quantity or thecomposition of the solvent in which the oil is dissolved, by adding, forexample, more `of the solvent already present in the solution, or byadding a new liquid diluent or other solvent; for instance, liquidSoz-benzol solution, Chlorex dichloroethyl ether) alone or ln solutionwith benzol, or furfural-benzol solution may be used in conjunction withour invention. This may be conveniently Veffected by introducing asuitable modifying solvent from the source 4 by means of the pump 20.

We found it possible to separate by our method mineral oils intofractions of different chemical characteristics, as indicated, forexample, by the temperature-viscosity relationships of diierentfractions, as well as of diierent boiling rangesthe manner of separationbeing dependent on the solvent and/or gaseous treating agent used.

In order to illustrate some of the applications of our invention, thefollowing examples are set forth, without intending, however, to limitthis invention to any specific features of these examples.

Eample I.-A topped Urycz crude was deasphaltized by dissolving it inabout 5-10 volumes of a liquid propane-butane fraction. After theprecipitated asphalt was separated, the propanebutane-oil solution wassaturated with a dry natural gas under a pressure of about 40atmospheres at a room temperature. A second heavy dark-colored phase wasformed and removed. The light phase was further saturated with the samegas and at the same temperature, but under a pressure of about 100atmospheres, whereby a new heavy phase was caused to separate, leavingin the secondary light phase a highly deasphaltized oil.

Example II.-A topped crude having specic gravity .9565 at C. and Englerviscosity of 3.03 at 100 C. was dissolved in 10 volumes of a liquidpropane-butane fraction. After the separation of precipitated asphalticsubstances, a natural gas consisting substantially of methane and ethane(from Daszawa) under a pressure of about 150 atmospheres was introducedinto the deasphaltized solution, which was maintained at roomtemperature. Under these conditions a heavy liquid layer containing17.08% of the original topped crude sample separated out. The oilseparated from the lighter phase had specific gravity .9325, a goodcolor and a viscosity index of 37 (609 sec. Say. at 100 F., 58.6 sec. at210 F.) a duplicate run produced the corresponding oil having aviscosity index of 4l. For comparison, a vacuum distillate from the samecrude and having specific gravity .9377 had a viscosity index of 21 (532sec. Say. at 100 F., 54.9 sec. at 210 F).

Eample III.-A sample of the same topped crude as was used in the ExampleII was dissolved in 3 volumes of a liquid propane-butane fraction; thiswas accompanied by precipitation of asphalt, which was removed. Thepropanebutane-oil phase was saturated with a dry natural gas, consistingsubstantially of CI-I4 and CHaCHs, under a pressure of 75 atmospheres ata room temperature; at this pressure a second phase containing about 33%of original oil, which consisted mainly of heavier and darker-coloredcomponents of the oil, separated out. The phases were separated and thelighter one was then saturated with the same gas under a pressure of 100atmospheres at the same room temperature; new phases were formed andseparated. Altogether the process-Was repeated four times with 4thefollowing results:

Fractionation of Urycz topped crude at room temperature At pressureSpecific Percent o'il precipitated atmosgravity Vlisncgty phares at 15C.

Example IV.-A heavy cylinder oil distillate of the followingcharacteristics:

Specic gravity at l5 C .9599 Viscosity Say. at 100 F sec-- 10,400Viscosity Say. at 210 F sec 222 Viscosity index 42 was dissolved in 3voliunes of a propane-butane fraction and then saturated with a drynatural gas at room temperature under a pressure of 60 atmospheres. Theprecipitated layer contained 48% of the original oil. After removingthis layer, the lighter phase was subjected to a treatment with the samenatural gas under 75 atmospheres, which resulted in the precipitation of39% of oil; the precipitated oil had a viscosity index of 51 (205 sec.Say. at 210 FJ. A further treatment under a pressure of 100 atmospheresproduced an oil with viscosity index of 74 (8l/2% of the original oil)Depending upon the required properties of oll fractions, the pressurechanges in the consecutive stages of our process may be quite small; inmany cases a. difference of five atmospheres at a substantially constanttemperature of the oil produces distinctly different oil fractions;generally, the greater is the change in pressure, the greater is theyield ofthe heavier phase. On the other hand, a lowering of the treatingoil temperature by 10 C., while maintaining a substantially constant gaspressure, may be suicient in some cases to effect the separation of agas-saturated oilr solution into two phases.

We are aware of the German patent to Metan No. 362,458 disclosing thedeasphaltizing eiect of dissolving an oil in liquefied normally gaseoushydrocarbons. However, our invention, as described, is directed to themethod of fractionating mineral oils by saturating them with gaseoussubstances incapable of being liqueed under the treating conditions ofour process, so that our process may be operated at temperatures, whichare beyond the critical temperature of the particular gaseous treatingagent which may be used in the process.

We claim as our invention:

l. In a process of separating a hydrocarbon oil into fractions havingdiferent properties, the steps of v'subjecting the oil to theprecipitating action of a quantity of a gaseous hydrocarbon treatingagent consisting substantially of at least one of the hydrocarbonshaving less than three carbon atoms per molecule, said precipitatingaction being exerted under a superatmospheric pressure below thecondensation pressure of said gaseous treating agent at the treatingtemperature, 'said quantity being-sufficient to cause the of saidgaseous formation of two liquid oil-containing phases of differentspecific gravities, and separating one phase from another.

2; Theprocessof claim 1 in which the gaseous treating agent is naturalgas.

3. The process of claiml in which the treating temperature is above thecritical temperature of the gaseous treating agent.

4. In a process'of separating a hydrocarbon oil into fractions havingdifferent properties, the steps of dissolving the 'oil in a liquiddiluent for s aid oil, subjecting the resulting solution to theprecipitatingV action of a quantity of a gaseous hydrocarbon treatingagent consisting substantially of at least one of the hydrocarbonshaving less'than three carbon atoms per molecule, said precipitatingaction being exerted under a superatmospheric pressure below` thecondensation pressure of said gaseous treating agent at the treatingtemperature, said quantity being sufficient to cause the formation oftwo liquid oilcontaining phases of different specific gravities,

and separating one phase from another.

5. In a process of separating a hydrocarbon oil into fractions havingdifferent properties the steps of dissolving the oil in a liquidhydrocarbon diluent having more than two carbon atoms per molecule,introducing into the resulting solution a quantity of a gaseoushydrocarbon treating agent consisting substantially of at least one ofthe hydrocarbons having less than three .carbon atoms per molecule undera superatmospheric pressure below Ythe condensation pressure of saidgaseous treating agent at the treating tempera# ture, said quantitybeing sufficient to cause the formation of two liquid oil-containingphases of different specific gravities, and separating one phase fromanother.

. 6. In a process of separating a hydrocarbon oil into fractions havingdifferent properties the steps of dissolving the oil in a liquidnaphthenic solvent,V introducing into the resulting solution a quantityof; a gaseous hydrocarbon treating agent` consisting substantially of atleast one of the hydrocarbons having -less than three carbon atoms permolecule under a superatmospheric pressure below the condensationpressure of said gaseous treating agent at the treatingtemperature, saidquantity being sufficient to cause the formation of two liquidoil-containing phases of different specific gravities, and separatingone phase from another.

v'7. .In a process r.of separating a hydrocarbon oil into fractionshaving different properties, the steps of subjecting the oil to theprecipitating action of a quantity of a gaseous hydrocarbon treatingagent -consisting substantially of at least one of the hydrocarbonshaving less than threevcarbon atoms per molecule, said precipitatingaction being exerted under a superatmosphericpressure below thecondensation pressure treating agent at the treating temperature, saidquantity being sufcient Vto cause the formation of two liquidoil-containing phases of different specific gravities, separating onephase from another, subjecting ythe separated liquid phase of lowerspecic gravity to the precipitating faction of another quantity of agaseous hydrocarbon treating agent consisting substantially of at leastone of the hydrocarbons having vless than three carbon atoms permolecule,r said precipitating action being exerted unfder asuperatmospheric pressure below the condensation pressure of saidgaseous treating agent 4 at4 the` treating temperature, said secondquanti- Cil 'ty of the treating agent being sufficient to cause theformation of two liquid oil-containing phases of different specificgravities, and separating one phase fromanother.

8. vIn a process of separating a hydrocarbon oil into fractions havingdifferent properties, the stepsof subjecting the oil to theprecipitating action-of a quantity of a gaseous hydrocarbon treatingagent consisting substantially of at least one of the hydrocarbonshaving less than three carbon atoms per molecule, said precipitatingaction being exerted under superatmospheric pressure and at atemperature abovethe critical 'temperature of the gaseous treatingagent, said quantity being sufficient to cause the formation of twoliquid loil-containing phases of different specific gravities, andseparating ane phasefrom another.

9. In a process of separating a hydrocarbon oil into fractions havingdifferent properties, the steps of subjecting the oil to theprecipitating action of a quantity of a gaseous hydrocarbon treatingagent consisting substantially of Aat least one of the hydrocarbonshaving less than three carbon atoms per molecule, said precipitatingaction being exerted under a pressure and at a temperature above thecritical pressure and critical temperature, respectively, of the gaseoustreating agent, said quantity being sufficient to cause the formation oftwo liquid oil-containing phases of different specific gravities, andseparating said liquid phases one from the other.

10.V In a process of separating a hydrocarbon y oil into fractionshaving different properties, the

steps of subjecting the oil to the precipitating action of a quantity ofa normally gaseous hy.- drocarbon treating agent, said precipitatingaction being exerted under a pressure and ata temperature above thecritical pressure and crit'- ical temperature, respectively, of thegaseous treating agent, said quantity being suflicient to causethe-formation of two liquid oil-containing phases of different specificgravities, and separating said liquid phases one from the other.

l1. In a process of separating a, hydrocarbon oil into fractions havingdifferent properties, the steps of subjecting the oil to theprecipitating action of a quantity of a gasiform light hydrocarbontreating agent, said precipitating action being exerted under a pressureand at a temperature above thev critical pressure and criticaltemperature, respectively, of the gasiform treatring agent, saidquantity being suflicient to cause theformation of two liquidoil-containing phases of different specific gravities, and separatingsaid liquid phases one from the other.

12. In a process of separating a hydrocarbon `oil into fractions havingdifferent properties, the

steps of subjecting the oil to the precipitating action of a quantity ofa gaseous hydrocarbon treating agent consisting substantially of atleast one of the hydrocarbons having less than three carbon atoms permolecule, said precipitating action being exerted at progressivelyvarying pressures above the critical pressure of the gaseous treatingagent and at a temperature above the critical temperature of the gaseoustreating agent, said quantity being sufficient to cause the formation oftwo liquid oil-containing phases of different specific gravitiesv andseparating said liquid phases one from the'other.

13. In a process of separating a hydrocarbon oil into fractions havingdifferent properties, the steps of subjecting the oil to theprecipitating action of a quantity of a gaseous hydrocarbon treatingagent consisting substantially of at least one of the hydrocarbonshaving less than three carbon atoms per molecule in the presence of aliquid naphthenic solvent, said precipitating action being exerted undera pressure and at a temperature above the critical pressure and criticaltemperature, respectively, of the gaseous treating agent, said quantitybeing suflicient to cause the formation of two liquid oil-containingphases of different specic gravities, and separating said liquid phasesone from the other.

14. Process for separating hydrocarbon material into constituent partswhich comprises extracting the hydrocarbon material with a normallyliqueable gaseous hydrocarbon solvent at a temperature above thecritical temperature of the liqueable hydrocarbon solvent and varyingthe density of the liqueable hydrocarbon solvent by a progressive changein pressure and by the addition to the liqueable hydrocarbon sol- 20vent of a substance misclble therewith and capable of changing itsdensity.

15. Process according to claim 14 in which the substance added to changethe density is a nonhydrocarbon substance.

16. A process for separating a mineral oil containing a normally gaseoushydrocarbon and normally liquid hydrocarbons into constituent partscomprising the steps of Varying the density of the normally gaseoushydrocarbons and precipitating normally liquid hydrocarbons to form aliquid phase heavier than said material, by a change in pressure withoutthe addition of heat at a temperature above the critical temperature ofthe normally gaseous hydrocarbon, and separating said heavier liquidphase from the unprecipitated portion of said hydrocarbon material.

STANISLAW PILAT. MARIAN GODLEWICZ.

